The method describes alternative culture media to OFS agar and SSL broth.
All beer-based beverages, lemonades, base products and sugar.
In addition to OFS agar and SSL broth, other culture media can be used as an alternative.
Determination of glucuronolactone by means of ion chromatography and pulsed amperometric detector
This method is suitable for energy drinks and non-alcoholic beverages.
Glucuronolactone is separated by means of a strongly alkaline eluent with an ion exchange column. It is detected and quantified electrochemically using a pulsed amperometric detector (PAD).
Through creating a potential, the ions are oxidized on a gold electrode and induce a measurable charge. To prevent the electrode from being coated over a short time, the potential is then reversed to reduce and release the ions from the electrode.
Product spoilage can be divided into different categories depending on the type of microbiological contamination.
The method describes the harmfulness of microorganisms in beer-based beverages.
The beer-based beverage segment includes beverages with a wide variety of compositions.
Both clear and yeasty beers are used in the mix. The proportion of beer varies between 30 and 90 %. Clear or fruit-flavoured soft drinks are used. Various sweetening components are also used. The pH value of the finished beverage can vary greatly from product to product. These diverse influencing factors have an affect on the microflora, which can negatively impact the respective product.
Table 1 provides an overview of the harmfulness of microorganisms in mixed-beer beverages.
Detection of fermentable yeasts and bacteria using a pour plate after prior liquid enrichment.
All cloudy beer-based beverages and lemonades.
The sample, which has been pre-enriched in SSL broth, is suspended in culture medium (OFS agar), incubated and analysed.
Determination of glucose and fructose by enzymatic means.
Suitable for beers, mixed beer beverages, malt beverages, non-alcoholic soft drinks, NAB, juices and drinks.
Glucose is phosphorylated by the enzyme hexokinase (HK) and adenosine 5'-triphosphate (ATP) to glucose 6-phosphate (G-6-P).
\(\text{Glucose + ATP} \space ^{\underrightarrow{\text{HK}}} \space \text{G-6-P + ADP}\)
In the presence of the enzyme glucose-6-phosphate dehydrogenase (G6P-DH), G-6-P is oxidized by nicotinamide adenine dinucleotide phosphate (NADP+) to gluconate-6-phosphate. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is formed:
\(\text{G-6-P + NADP}^+ \space ^{\underrightarrow{\text{G6P-DH}}} \space \text{gluconate-6-phosphate + NADP + H}^+\)
The amount of NADPH formed during the reaction is equivalent to the amount of glucose. NADPH is determined based upon its absorbance at 340 nm.
Note:
Alternatively, NAD+/NAD + H+ can be used instead of NADP+/NADP + H+:
\(\text{G-6-P + NAD}^+ \space ^{\underrightarrow{\text{G6P-DH}}} \space \text{Gluconate-6-Phosphate + NAD + H}^+\)
Detection of harmful yeasts and bacteria by means of membrane filtration and subsequent incubation on OFS agar.
All clear beer-based beverages and lemonades.
The sample is membrane-filtered, incubated and analysed.